Hybrid supercritical carbon dioxide geothermal systems

ABSTRACT

Provided herein are geothermal power generating systems utilizing supercritical carbon dioxide as a working fluid and superheating the extracted the emitted carbon dioxide utilizing external combustion of the hydrocarbons concurrently extracted with the emitted carbon dioxide to increase enthalpy and thermodynamic cycle efficiency. Methods for producing power are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional patent applicationU.S. No. 61/526,260 titled “Hybrid Supercritical Carbon DioxideGeothermal Systems” filed on Aug. 22, 2011, and hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to power generation utilizingthermal energy first as extracted from a geothermal source and secondlyfrom concurrent hydrocarbons extracted from the same geothermal sourcesubsequently combusted to superheat the carbon dioxide working fluidutilized both from the geothermal source and within the thermodynamiccycle of the power generation system. In all embodiments, the presentinvention utilizes at least one power generating cycle producing CO2containing emissions and with at least one power generating cycle usingsupercritical carbon dioxide “ScCO2” as a working fluid and solubilizeshydrocarbons that are concurrently extracted from the geothermal source.

BACKGROUND OF THE INVENTION

Energy efficiency has important impact on both economics of operatingcosts and carbon dioxide “CO2” emissions. The production of power fromhydrocarbon fuels and from geothermal thermal sources are individuallyknown in the art. The combustion of fuels, whether it be hydrocarbons,biomass, biofuels, or coal as known in the art yields CO2 emissions. Itis known in the art that these CO2 emissions can reach elevatedpressures as sufficient for injection into a geothermal injection wellby a wide range of compressors, pumps, etc. as known in the art. Onesuch source of carbon dioxide is the combustion of coal or hydrocarbonsfor a wide range of applications ranging from dedicated power generationsystems to industrial processes.

Traditional power generation cycles using supercritical carbon dioxide“ScCO2” have distinct challenges associated with at least one of CO2leakage from the otherwise closed loop cycle, and the direct impact ofCO2 within the high pressure side of the closed loop cycle on the lowpressure side of the closed loop cycle and vice versa.

Traditional power generation cycles using ScCO2 heated by a geothermalsource such that the ScCO2 is the working fluid in the power generationcycle and a geothermal heat transfer fluid is the fluid extractingthermal energy from the geothermal source are both known in the art.Additionally, the use of ScCO2 as both the working fluid in the powergeneration cycle and the geothermal heat transfer fluid (i.e., the“same” ScCO2 is used for both) is also known in the art.

The combined limitations of existing power generation systems utilizingScCO2 as the working fluid include, though not limited to, CO2 leaks,insufficient high-side temperature (i.e., insufficiently high geothermalsource temperatures), or fluid components or combustion byproducts ofthose fluid components that are concurrently extracted from thegeothermal extraction well that are condensed within the powergeneration expander.

SUMMARY OF THE INVENTION

The present invention preferred embodiment relates to the combustion ofsolubilized hydrocarbons to increase enthalpy and exergy of a ScCO2power generation system. In the preferred embodiment, the combustionbyproducts include CO2 that is subsequently injected into the geothermalinjection well to minimize CO2 requirements to make up for geothermalleaks, geothermal mineral carbonation, and power generation workingfluid leaks all if which consume or contribute to CO2 losses.

Another embodiment incorporates a dual stage expander to enable maximumenergy extraction of the CO2 and the combustion byproducts injected intothe CO2 working fluid, and the subsequent reduction of condensables(i.e., a portion of the combustion byproducts e.g., water) prior toreaching a second stage expander.

Yet another embodiment incorporates a ceramic expander, preferably aramjet expander, to enable maximum energy extraction of the CO2 and thecombustion byproducts injected into the CO2 working fluid, such that thecondensables (i.e., a portion of the combustion byproducts e.g., water)limit any damage within the expander, and virtually eliminate therequirement to separate condensables from the CO2 working fluidpost-expander.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sequential flow diagram of one embodiment of a geothermalsource power generation system utilizing an external thermal source, inthis example being a solar energy through a CO2 receiver and heat pump,in accordance with the present invention;

FIG. 2 is a sequential flow diagram of one embodiment of a geothermalsource power generation system utilizing an external thermal source, inthis example being hydrocarbon combustion solubilized within the CO2working fluid of the power generation system, in accordance with thepresent invention;

FIG. 3 is another sequential flow diagram of one embodiment of ageothermal source power generation system utilizing an external thermalsource, in this example being hydrocarbon combustion solubilized withinthe CO2 working fluid of the power generation system, in accordance withthe present invention;

FIG. 4 is another sequential flow diagram of one embodiment of ageothermal source power generation system utilizing an external thermalsource, in this example being hydrocarbon combustion solubilized withinthe CO2 working fluid of the power generation system, in accordance withthe present invention;

FIG. 5 is a flow diagram of one embodiment of a geothermal source powergeneration system utilizing a dual stage expander with condensablesbeing discharged in between the 2 stages, in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The term “in thermal continuity” or “thermal communication”, as usedherein, includes the direct connection between the heat source and theheat sink whether or not a thermal interface material is used.

The term “fluid inlet” or “fluid inlet header”, as used herein, includesthe portion of a heat exchanger where the fluid flows into the heatexchanger.

The term “fluid discharge”, as used herein, includes the portion of aheat exchanger where the fluid exits the heat exchanger.

The term “expandable fluid”, as used herein, includes the all fluidsthat have a decreasing density at increasing temperature at a specificpressure of at least a 0.1% decrease in density per degree C.

The term “working fluid” is a liquid medium utilized to convey thermalenergy from one location to another. The terms heat transfer fluid,working fluid, and expandable fluid are used interchangeably.

The term “supercritical” is defined as a state point (i.e., pressure andtemperature) in which a working fluid is above its critical point. It isunderstood within the context of this invention that the working fluidis supercritical at least on the high side pressure of a thermodynamiccycle, and not necessarily on the low side of the thermodynamic cycle.

The term “ramjet” is a rotary device that eliminates the need for aconventional bladed compressor (when a ramjet compressor) and turbine(when a ramjet expander) as used in traditional gas turbine engines. Oneembodiment of a ramjet is an inside-out supersonic circumferential rotorhaving integrated varying-area shaped channels in its radially inwardsurface, in which compression, combustion and expansion occur. The“inside-out” design places all rotating parts under compressivecentrifugal loading.

The term “CO2 source” is an air composition that contains carbon dioxideranging from 5 percent on a mass fraction basis to a highly enriched aircomposition up to 100 percent on a mass fraction basis.

The term “fuel” is a chemical reactant that is exothermic during anoxidation reaction. In this invention, it is preferred to be asolubilized hydrocarbon.

The term “CO2 capture system” is a method of effectively isolatingcarbon dioxide from an air composition, such as combustion exhaust, byany method ranging from carbonation chemical reaction, adsorption, orabsorption. The process of isolating carbon dioxide is reversible suchthat an increase of temperature beyond a critical point changes theequilibrium point.

The term “recuperator” is a method of recovering waste heat downstreamof an expander and transferring the thermal energy upstream of either acompressor, turbocompressor or pump.

The term “exhaust port” is any method capable of discharging a workingfluid that can include safety valve, pressure regulated valve, expansiondevice venting to atmosphere, etc.

The term “pressure increasing device” is any device capable ofincreasing the pressure of a working fluid, include a turbocompressor,turbopump, compressor, or pump.

The term “expander” is any device capable of decreasing the pressure ofa working fluid, including a turboexpander, piston, or ramjet expanderwhile converting the expansion energy into mechanical energy (andpotentially then to electricity).

The term “high-side” is the high pressure side of a closed loopthermodynamic cycle such that the high-side is downstream of a pressureincreasing device and upstream of an expander device.

The term “low-side” is the low pressure side of a closed loopthermodynamic cycle such that the low-side is downstream of an expanderdevice and upstream of a pressure increasing device.

Here, as well as elsewhere in the specification and claims, individualnumerical values and/or individual range limits can be combined to formnon-disclosed ranges.

Exemplary embodiments of the present invention will now be discussedwith reference to the attached Figures. Such embodiments are merelyexemplary in nature. Furthermore, it is understand as known in the artthat sensors to measure thermophysical properties including temperatureand pressure are placed throughout the embodiments as known in the art,most notably positioned to measure at least one thermophysical parameterfor at least one thermodynamic state point. The utilization of valves asstandard mass flow regulators is assumed (i.e., not depicted) to be asknown in the art and can also include variable flow devices, expansionvalve, turboexpander, two way or three way valves. The utilization ofmethods to remove heat from the working fluid by a condensor (usedinterchangeably with condenser) is merely exemplary in nature as athermal sink and can be substituted by any device having a temperaturelower than the working fluid temperature including absorption heat pumpdesorber/generator, liquid desiccant dehumidifier, process boilers,process superheater, and domestic hot water. With regard to FIGS. 1through 5, like reference numerals refer to like parts.

It is understood that virtually every embodiment of this invention canstart with CO2 sourced by industrial or power generation processes suchas calciners, high temperature furnaces, and fuel combustorsrespectively.

Every configuration and embodiment has a control system and method ofcontrol to operate the power generation cycle(s) and to obtain optimalcontrol of a geothermal and externally superheated ScCO2 cycle.

The availability of geothermal energy is recognized as a relativelysteady state thermal source of energy subsequently utilized to convertthermal into mechanical energy through a Rankine thermodynamic cycle. Itis also recognized by prior art that carbon dioxide reacts withminerals, often found within the earth's surface, to yield an exothermicreaction. It is also recognized that carbon dioxide, particularlysupercritical carbon dioxide “ScCO2” is a solvent for many organicfluids, such as hydrocarbons present in the earth's surface. Thereforethe combination of carbon dioxide as a working fluid within a semi-opengeothermal loop has the ability to increase the temperature of thereturning ScCO2 greater than alternative Rankine cycle working fluids.And concurrently has the ability to return solubilized hydrocarbons,plus additional fluid constituents (e.g., water, minerals, etc.). It isunderstood that supercritical carbon dioxide is an excellent solvent fora wide range of materials, notably hydrocarbons.

This invention preferably combines the exothermic reaction of mineralcarbonation with the exothermic oxidation reaction of the solubilizedhydrocarbons as a method to increase the high-side temperature of theRankine cycle, which yields greater energy production per mass flow ofScCO2. It is understood that solubilized hydrocarbons

Turning to FIG. 1, FIG. 1 depicts an in-situ geothermal thermal loop inseries with a subsequent solar receiver where the geothermal loop, solarloop, and Rankine cycle all have the same working fluid to generatepower. The solar loop, which is comprised of at least one solar receiverheat exchanger 20 operable to increase the enthalpy of the ScCO2 workingfluid. The now superheated, relative to the fluid directly from thegeothermal extraction well 210, increases the operating efficiency ofthe Rankine cycle by at least 5 percent, more preferably by at least 10percent, and more specifically by at least 20 percent. The solarreceiver 20 is optimally configured in a heat pipe configuration suchthat the condenser herein labeled as solar thermal heat pipe 11 is abovethe solar receiver. It is understood in the art that the solar receiverHX 20 can be flat panels, parabolic trough, or tower and/or combinationsthereof. The now superheated ScCO2, which is downstream of the solarthermal heat pipe 11 (acting as condenser) is in fluid communicationwith the ScCO2 expander 40. The now low pressure ScCO2 continues to theScCO2 condensor 60 prior to reaching the ScCO2 pump 30 (which can alsobe a turbopump, or even a turbocompressor if operating as a Braytoncycle instead of Rankine cycle). The ScCO2 at this point is highpressure prior to being injected in the injection well 200.

Turning to FIG. 2, FIG. 2 depicts an in-situ geothermal thermal loopsuch that working fluid out of the extraction well 210 is comprised ofat least 0.5 percent of hydrocarbons (and preferably greater than 1percent, more preferred greater than 5 percent by volume) having anenergy content greater than 5 percent by enthalpy over the working fluiditself (and preferably greater than 10 percent, and more specificallypreferred greater than 20 percent) in which the hydrocarbons areseparated from the working fluid for subsequent combustion. One of thepreferred embodiments is such that the phase separator 220 isimmediately downstream of the extraction well 210. The phase separator220 can be any type of separator as known in the art, including suchdevices as membrane filters, or centrifugal fluid isolators. The phaseseparator 220 isolates at least 50 percent of hydrocarbons from theworking fluid (and preferably at least 80 percent of hydrocarbons). Itis understood that the hydrocarbons can still contain water/steam,though preferably the phase separator isolates the hydrocarbons from theworking fluid and also from the water/steam. The hydrocarbons then enteran optional liquid atomizer 230, which as known in the art is any methodto reduce particle size of the emitted hydrocarbons as a means toincrease combustion efficiency, and then enters an optional recuperator390.1 operable to preheat the hydrocarbons prior to entering theexternal combustor HX 220. The preferred embodiment is such that thehydrocarbons are diluted with at least 10 percent by volume, such aswith ScCO2, to enhance combustion efficiency. This embodiment has thecombustion exhaust being vented to atmosphere downstream of the externalcombustor HX 220. The ScCO2 (at least concentrated CO2) downstream ofthe phase separator 220 enters the external combustor HX 220 to increasethe enthalpy of the ScCo2 working fluid upstream of the ScCO2 expander40. The external combustor 220 is operable to increase the enthalpy ofthe ScCO2 working fluid. The now superheated, relative to the fluiddirectly from the geothermal extraction well 210, increases theoperating efficiency of the Rankine cycle by at least 5 percent, morepreferably by at least 10 percent, and more specifically by at least 20percent. The external combustor can also be configured as a thermal heatpipe in the same manner as in FIG. 1. As noted earlier, the now expandedScCO2 working fluid (subcritical when operable as a Rankine cycle, orsupercritical when operable as a Brayton cycle) enters the optionalrecuperator 390.1 prior to entering the ScCO2 condensor 60, and thenprior to entering ScCO2 pump (which can also be a turbopump, or even aturbocompressor if operating as a Brayton cycle instead of Rankinecycle). The now high pressure working fluid enters the injection well200 to begin the cycle anew. It is understood that the hydrocarbons aremixed with an oxidant source, most notably atmospheric air at astoichiometric excess to ensure full combustion of the hydrocarbons asknown in the art.

Turning to FIG. 3, FIG. 3 is identical to FIG. 2 with the followingexceptions. These exceptions include: a) placement of hydrocarbonsensors 240 as known in the art to detect mass or volumetric fraction ofhydrocarbons physically placed at least at the extraction well 210and/or upstream of the liquid atomizer 230 and downstream of the phaseseparator 220 (or at any point upstream of the external combustor HX220, preferably further away so as to provide more time to calculate thestoichiometric ratio between oxidant source and hydrocarbon content); b)oxidant compressor 250 for injection of the oxidant source into theexternal combustor HX 220; and c) combustion exhaust is not vented toatmosphere but rather injected at either (or both) upstream of the ScCO2expander 40 (A1 injection point) or immediately upstream of theinjection well 200 (A2 injection point). Though not shown, it isfeasible to inject the combustion exhaust within the low pressure sideof the Rankine cycle such that the then subsequent ScCO2 pump has theability to prepare the CO2 for well injection. The configuration in FIG.3 has numerous advantages which include reduced requirement of ScCO2(from any source, particularly when purchased or piped from a remotelocation), reduced CO2 emissions to the atmosphere, and increased powergeneration by expanding supercritical combustion byproducts into a lowerbut still supercritical pressure at a pressure of at least 5 psi greaterthan the injection well 200 pressure.

Turning to FIG. 4, FIG. 4 is virtually identical to FIG. 3 with the onlyexception being the oxidant compressor 250 (i.e., air compressor oroxygen compressor) is preheated by thermal energy as obtained by therecuperator 390 which receives CO2 working fluid downstream of the ScCO2expander 40 and upstream of the phase separator 220.

Turning to FIG. 5, FIG. 5 depicts a preferred expander (shown as ScCO2expander 40 in aforementioned FIGS. 1-4) that is a combinationcentrifugal phase separator and expander. The high pressure workingfluid 300, which in this embodiment is ScCO2, enters the expanderthrough a volute as known in the art. The higher density components(e.g., hydrocarbons, water/steam, etc.) are centrifugally distributed tothe outwardly radial inner wall of the expander. The now higher densitycomponents exit a break in the outwardly radial inner wall thus actingas in an identical manner as depicted within this figure as phaseseparator 220 (and also in other aforementioned figures). The ScCO2fraction of the working fluid continues to expand within the expanderuntil it finally reaches the exit of the expander at a low pressureScCO2 volute 310. The particularly preferred embodiment of thecentrifugal expander is an inside-out ramjet expander operable atrotation speeds “RPM” producing larger than 100 gravitational fieldforce, preferably greater than 1000 gravitational field force, morepreferred greater than 10,000 gravitational field force, andspecifically preferred greater than 100,000 gravitational field force.The high gravitational field force enhances both the speed of phaseseparation and importantly eliminating the requirement for two distinctdevices with one being expander and second being phase separator.

The preferred embodiment of the invention is a geothermal energy systemthat achieves superior performance by the inclusion of externalcombustion of hydrocarbons that are concurrently extracted with theworking fluid of the power generation cycle, which is primarily carbondioxide. It is understood that the extraction of the carbon dioxidecontaining working fluid includes a wide range of solubilized componentfractions notably hydrocarbons. Additional component fractions includewater (or steam as dependent on working fluid temperature and pressure)and minerals notably carbonates. The geothermal power generator, herebyknown as the reference power generator or first power generatorconfiguration does not include the external combustor that combusts theco-extracted hydrocarbons. The thermodynamic cycle has a preferredhigh-pressure side with a pressure greater than 1500 psi, particularlypreferred greater than 2000 psi, and specifically preferred greater than2500 psi. The thermodynamic cycle has a preferred low-pressure sidepressure lower than 800 psi, particularly preferred lower than 700 psi,and specifically preferred lower than 650 psi.

The external combustor contains an exothermic oxidation reaction betweenthe solubilized co-extracted hydrocarbons with an oxygen containing gas.The preferred oxygen containing gas is air, the particularly preferredoxygen containing gas has an oxygen composition fraction greater than25%, and the specifically preferred oxygen containing gas has an oxygencomposition fraction greater than 85%. It is understood that the lowerthe oxygen concentration leads to a combustion exhaust fraction that hasa relatively higher fraction of non-condensable gases. The presence ofthese non-condensable gases present cavitation challenges in the pump ofthe thermodynamic cycle. It is understood, though not depicted in thefigures, as known in the art that the inclusion of de-aerator upstreamof the pump approximately removes the non-condensable gases. It isfurther understood that the utilization of an inside-out ramjet, asknown in the art and comparable to the inside-out ramjet expander, canbe a compressor/pump. The particularly preferred compressor/pump ismanufactured using ceramic components, and the specifically preferredcompressor/pump is manufactured using ultra-hard ceramic componentsapproximately immune to cavitation damage. Furthermore, it is preferredthat the oxidant is compressed to a pressure above the high-pressureside of the thermodynamic cycle. This has the further advantage ofenabling the combustion exhaust to be utilized within the thermodynamiccycle reducing the concerns or challenges of carbon dioxidereplenishment to overcome carbon dioxide leaks within the system notablycompressor/pump and expander(s). An additional advantage ofsupercritical combustion is such that additional thermal energy istransformed into mechanical energy to increase power production.

Another preferred embodiment of the invention is such that the condenserwithin the thermodynamic cycle is not (i.e., void) of an atmospheric aircondenser. The particularly preferred condenser is a wet condenser, andthe specifically preferred condenser utilizes cold water as extractedfrom a water source approximately at the surface. The preferred depth isless than 2000 feet deep, the particularly preferred depth is less than1000 feet deep, and the specifically preferred depth is less than 500feet deep.

Utilization of the aforementioned invention as disclosed is a superiormethod of producing power from a geothermal source. It is furtherunderstood that additional hydrocarbons can be utilized to furtherincrease the superheat of the carbon dioxide containing working fluid.The combustion of these additional hydrocarbons at supercriticalpressures enables direct injection of the carbon dioxide exhaustbyproducts into the injection well for carbon dioxide sequestration,thus eliminating one of the primary concerns of less than optimalcombustion in the era of climate change.

What is claimed is:
 1. A geothermal energy system comprising a firstgeothermal power generator having an extraction well, an injection well,at least one thermodynamic cycle having a first working fluid containingat least carbon dioxide, the at least one thermodynamic cycle having anexpander, a condenser, a high-pressure side, a low-pressure side, and acycle efficiency; and a heat exchanger to superheat the first workingfluid containing at least carbon dioxide, a phase separator operable toisolate at least one hydrocarbon from the first working fluid containingat least carbon dioxide upstream of the extraction well, an externalcombustor operable to combust the at least one hydrocarbon whereby thecombusted hydrocarbon superheats the first working fluid containing atleast carbon dioxide, and the superheated first working fluid containingat least carbon dioxide is operable to increase the cycle efficiency byat least 5 percent greater than the first geothermal power generator. 2.The geothermal energy system according to claim 1 further comprised of arecuperator operable to preheat the at least one hydrocarbon.
 3. Thegeothermal energy system according to claim 1 further comprised of aliquid atomizer operable to reduce particle size of emitted at least onehydrocarbon diluted by at least 10 percent by volume of the firstworking fluid containing at least carbon dioxide.
 4. The geothermalenergy system according to claim 1 further comprised of an oxidant andan oxidant compressor operable to increase the oxidant pressure to apressure at least 5 psi greater than the low-pressure side pressure. 5.The geothermal energy system according to claim 1 further comprised ofan oxidant and an oxidant compressor operable to increase the oxidantpressure to a pressure at least 5 psi greater than the high-pressureside pressure.
 6. The geothermal energy system according to claim 1whereby the expander is a dual stage expander having a first stage and asecond stage operable to at least partially isolate the at least onehydrocarbon downstream of the first stage and upstream of the secondstage.
 7. The geothermal energy system according to claim 1 whereby theexpander is an inside-out ramjet expander.
 8. The geothermal energysystem according to claim 4 whereby the external combustor has acombustion exhaust comprising at least carbon dioxide and wherein thecombustion exhaust is injected upstream of the expander.
 9. Thegeothermal energy system according to claim 4 whereby the externalcombustor has a combustion exhaust comprising at least carbon dioxideand wherein the combustion exhaust is injected upstream of the injectionwell and downstream of the condenser.
 10. The geothermal energy systemaccording to claim 4 whereby the external combustor has a combustionexhaust comprising at least carbon dioxide and wherein the combustionexhaust is injected upstream of the expander.
 11. The geothermal energysystem according to claim 6 whereby the dual stage expander first stageis operable as both a centrifugal phase separator and expander.
 12. Thegeothermal energy system according to claim 6 further comprised of aphase separator operable to further isolate the at least partiallyisolated at least one hydrocarbon from water or steam upstream of theexternal combustor.
 13. The geothermal energy system according to claim7 wherein the inside-out ramjet expander produces a centrifugal forcegreater than 100 times the gravitational field force.
 14. The geothermalenergy system according to claim 7 wherein the inside-out ramjetexpander produces a centrifugal force greater than 1000 times thegravitational field force.
 15. A geothermal energy system comprising: anextraction well, an injection well, at least one thermodynamic cyclehaving a first carbon dioxide working fluid the at least onethermodynamic cycle having an expander and a cycle efficiency, acondenser, a heat exchanger to superheat the at least one thermodynamiccycle having the first carbon dioxide working fluid using a solarreceiver upstream of the expander is operable to superheat the firstcarbon dioxide working fluid of the at least one thermodynamic cycle,and the superheated first working fluid containing at least carbondioxide is operable to increase the cycle efficiency by at least 5percent greater than the first geothermal power generator through thesolar receiver.
 16. The geothermal energy system according to claim 15further comprised of an external combustor having a combustion exhaustcomprising at least carbon dioxide and wherein carbon dioxide from thecombustion exhaust is injected into the first carbon dioxide workingfluid of the at least one thermodynamic cycle.
 17. The geothermal energysystem according to claim 15 further comprised of at least onehydrocarbon from the first working fluid containing at least carbondioxide and an external combustor operable to combust the at least onehydrocarbon to increase the cycle efficiency by at least 5 percent. 18.The geothermal energy system according to claim 15 further comprised ofat least one hydrocarbon from the first working fluid containin at leastcarbon dioxide and an external combustor operable to combust the atleast one hydrocarbon to increase the cycle efficiency by at least 10percent.
 19. The geothermal energy system according to claim 17 wherebythe first carbon dioxide working fluid is further comprised of at least1 percent by volume of solubilized hydrocarbons.
 20. A method ofproducing power from a geothermal source, the method providing a firstgeothermal power generator comprising a extraction well, an injectionwell, at least one thermodynamic cycle having a first working fluidcontaining at least carbon dioxide, the at least one thermodynamic cyclehaving an expander, a condenser, a high-pressure side, a low-pressureside, and a cycle efficiency; and a heat exchanger to superheat thefirst working fluid containing at least carbon dioxide, a phaseseparator operable to isolate at least one hydrocarbon from the firstworking fluid containing at least carbon dioxide upstream of theextraction well, an external combustor operable to combust the at leastone hydrocarbon whereby the combusted hydrocarbon superheats the firstworking fluid containing at least carbon dioxide, and the superheatedfirst working fluid containing at least carbon dioxide is operable toincrease the enthalpy by at least 5 percent greater than the firstgeothermal power generator.